The covalent and non-covalent complex of β-glucan of oats and quercetin were prepared using radical catalysis and hydrogen bond adsorption methods, named COGQ and NOGQ, respectively. Their molecular structures were characterized using HPSEC (high performance size exclusion chromatography), FT-IR spectrometry and NMR (nuclear magnetic resonance) spectroscopy. The anti-aging activities of the complex were evaluated by Caenorhabditis elegans(C. elegans) model. Results from HPSEC showed that the relative molecular weights of NOGQ and COGQ were 354kDa and 349kDa, respectively, which were not much different. Compared with β-glucan of oats, both complexes demonstrated several new infrared absorption peaks at 1660cm-1, 1243cm-1 and 1562cm-1 and polysaccharide and polyphenols conjugates are amorphous. According to the NMR data, three monosaccharide residues were observed in the anomeric region of ¹H spectrum and three new proton signals at 6.5-8.5 were attributed to phenyl groups in the complex. Compared with the control group, COGQ and NOGQ significantly increased the average lifespan of C. elegans (P<0.05), and the activities of SOD and CAT in both groups were significantly increased (P<0.01), suggesting that COGQ and NOGQ composites may prolong the lifespan of C. elegans by improving the antioxidant capacity of the body. The results could provide a reference for the preparation of polysaccharides and polyphenol composites and the development and utilization of them as novel food antioxidants.